In the art of respiration devices, there are well known variety of respiratory masks which cover the nose and/or mouth of a human user in order to provide a continuous seal around the nasal and/or oral areas of the user's face such that gas may be provided at positive pressure within the mask for consumption by the user. The uses for such masks range from high altitude breathing (i.e., aviation applications) to mining and fire fighting applications, to various medical diagnostic and therapeutic applications.
One application of such a mask is in respiratory humidification treatment. This system normally consists of a ventilator, humidifier, breathing circuit and user interface, being a mask. In this form of treatment humid air is supplied to the patient and as a result of the temperature difference between the humid air and the surrounding environment, the humid air can condense and form water droplets. In cases where treatment is prolonged (up to several days) these droplets may form water pools in the mask that can hamper the treatment, increase the risk of the patient inadvertently inhaling water and may cause discomfort to the patient.
One requisite of such respiratory masks has been that they provide an effective seal against the user's face to prevent leakage of the gas being supplied. Commonly, in prior mask configurations, a good mask-to-face seal has been attained in many instances only with considerable discomfort for the user. This problem is most crucial in those applications, especially medical applications, which require the user to wear such a mask continuously for hours or perhaps even days. In such situations, the user will not tolerate the mask for long durations and optimum therapeutic or diagnostic objectives thus will not be achieved, or will be achieved with great difficulty and considerable user discomfort.
U.S. Pat. Nos. 6,196,223 and 6,341,606 are examples of prior art that attempts to improve the mask system. U.S. Pat. No. 5,715,814 is an example of an attempt to improve the mask scaling mechanism,